A significant number of improvements to windscreen or windshield wiper systems have been made since the early 1970's. During a period of increasing automotive manufacturer awareness of the need for additional safety on the nation's highways, a correlative development in the instant art took place. As speeds increased, along with trip distances, better driver vision through the windscreens or windshields was mandated. To this end, the automotive world saw the advent of automatic windshield wipers, windshield washers, and alterations of windshield geometry in order to give a better and clearer field of vision. During inclement weather, the most noticeable degradation of safety is the likelihood of sliding or striking obstructions in the road. The former, although not directly attributable to reduced vision, is nonetheless compounded by it; and, the latter is undoubtedly caused by reduction in vision. Rain and mud spattering can be adequately removed by the traditional wiper blade; however, the addition of automatic windshield washing, although making the cleansing activity easier, did nothing to extend an already diminished field of vision. In a patent issued to Brigmon in 1958, U.S. Pat. No. 2,829,394, an invention was presented that appeared to anticipate the aforementioned problems and effectively clean a much wider area of the windshield. The device of Brigmon envisioned a wiping blade that traversed a windshield motivated by an arcuate sweeping arm (in the traditional fashion) but that was captured at the top and bottom of the blades by parallel grooves. No evidence exists to disclose why such a device never became the norm in windshield cleaning; but, it appears to this inventor that the strong likelihood of material fouling of at least the lower groove could probably frustrate proper operation of the Brigmon invention. Failure of the windshield wiper system entirely, during a time of extreme need, is indeed a serious drawback.
An invention relating to a reciprocating windshield wiper blade was disclosed in U.S. Pat. No. 3,831,220 which issued to Gmeiner in 1974. In this windshield wiper system, the rotary motion of a drive source is, through a link coupling, converted to a reciprocating motion that is applied to the main wiper blade of the windshield wiper system. The main wiper blade is compelled to move outward during the major portion of its sweep so that its tip nearly touches the top margin of the windshield. A rather severe disadvantage of this type invention is that, as more area near the top of the windscreen is swept clean by the extended blade, a greater portion in the lower part of the windscreen is left unswept. For this invention, the concomitant loss of a smaller portion near the bottom of the windshield was evidently considered worthwhile. Such a hand-off, however, does not serve the instant inventor's purpose.
Four other U.S. patents issued to Krohm, Sigety, Schuech, and Leroy, U.S. Pat. Nos. 2,979,752, 4,418,440, 4,447,928, and 4,584,734, respectively, are contributions and improvements to the windshield wiper art. Krom modifies the area of sweep of the windshield wiper by modifying the movement of the blade proper. On the other hand, Sigety uses a telescoping wiper arm which extends and retracts (reciprocates) on the guide arm, out of and into a wiper arm, as it is driven by an endless belt drive means. It is noteworthy that Sigety's mechanism telescopes from the wiper arm rather than from the main wiper blade assembly. Thus, as in the Gmeiner invention, any new area coverage by the extension of the wiper blade concomitantly omits a similar geometry (albeit a smaller one) at the base of the windshield. Schuech effectively teaches the Sigety invention, but does so using a different mechanical means (through lever arms and cams) to reciprocate the wiper blade. The aforementioned major disadvantages of the Gmeiner and Sigety inventions still obtains in the Schuech invention. The same summary and conclusions also apply to the invention disclosed by Leroy.
Thus, the major disadvantages of the extant prior art, and which have been effectively overcome by the instant invention, were the inability to wipe larger areas of a windshield or windscreen, with a seemingly conventional type windshield wiper blade, without sacrificing the cleaning of other areas of the windshield. To individuals of shorter stature, a loss of lower windshield cleansing would appear most significant. To the extent that some developments were made and taught using the art of extending a blade, none appeared to literally extend the blade proper and, in all cases, the mechanisms that were used to reciprocate the main blade appeared highly mechanistic, involved, and often laboriously contrived.